Multiple feed-through capacitor and methods of making

ABSTRACT

A ceramic plate is formed with sleeve-like protuberances with an internal aperture, the plate is metalized around the sleeve-like protuberances, and feed-through conductors are placed through the apertures, the metallized coating around the protuberances and the feedthrough conductor forming the capacitance; the metalized coating is removed from the zones surrounding the terminal ends of the openings, to provide ceramic insulation material between the feed-through conductors and the metalized coating. The metalized coating may be removed by grinding.

United States Patent '[191 I Winkler Apr. 30, 1974 [54] MULTIPLE FEED-THROUGH CAPACITOR 2,940,058 6/1960 Foster 333/79 METHODS OF G FOREIGN PATENTS OR APPLICATIONS [75] lnvemo" :Xg Rothenbach 878,205 9/1961 Great Britain 317/242 [73] Assignee: gtettnzr & C0., Lauf/Pegmtz, Primary A. Go dberg erm my Attorney, Agent, or Firm-Flynn & Frishauf [22] Filed: July 30, 1973 [21] Appl. No.: 383,531 [57] ABSTRACT [30] Foreign Application Priority Data A ceramic plate is formed with sleeve-like protuber- A 5 1972 G 2238594 ances with an internal aperture, the plate is metalized emany around the sleeve-like protuberances, and feedthrough conductors are placed through the apertures, [52] Cl 317/242 29/2542 47 the metallized coating around the protuberances and [51] Int Cl H01 3/28 the feedthrough conductor forming the capacitance; [58] Fieid 29/35 42 the metalized coating is removed from the zones sur- I 33/79 rounding the terminal ends of the openings, to provide ceramic insulation material between the feed-through [56] References Cited conductors and the metalized coating. The metalized UNITED STATES PATENTS coating may be removed by grinding.

3,246,215 4/1966 Rieth 317/242,

' 11 Claims, 14 Drawing Figures The present invention relates to a multiple feedthrough capacitor, particularly for use in electronics, for example to conduct feed-through conductors through shielded enclosures, and to a method of making such capacitors.

F eed-through capacitors, particularly for multiple use are employed in electronics to permit passage of low frequency signals through the conductors, but to bypass high frequency signals, noise signals, or the like to chassis, or ground, by connecting the feed-through lead to a capacitor, the other side of which is connected to ground. For various frequencies and capacities of the capacitors, ceramic feed-through capacitors are used, the capacity of which depends on the dielectric material and may be in the range of, for example, about 400pF to 2,000pF.

Single feed-through capacitors which are connected into a shielded enclosure wall, and a connection of the associated elements are comparatively expensive. In high frequency apparatus it has been attempted to utilize multiple feed-through capacitors whichare then connected to printed circuit plates, or similar elements in one single manufacturing step by dip soldering, or

the like. The feed-through capacitors, or the printed circuits are then connected together with a support block, or support plate on a carrier, for example a carrier plate to be sealed with respect to high frequency signals within the shielded housing. Various examples of such feed-through capacitors to be used with shielded housings are described in German disclosure document 1,439,298; a common socket is used in that construction, in which the feed-through conductors are metallically connected with one metal sheet, or layer, and the conductors are formed at the other ends as connecting pins, or with solder terminals. Small ceramic tubes are used as the dielectric, the tubes being internally and externally silvered, the interior silver coating being soldered to the feed-through conductor.

To assemble such feed-through conductors in a shielded enclosure, and to connect the conductors, requires a considerable amount of labor, and the ceramic tube must be secured within a bore of the mounting block or strip by means of an adhesive first placed into the mounting hole. Thereafter, the ceramic tube must be connected to a metal lead, typically by a screw con- I nection, for example by screwing the outside silvered ceramic sleeve or tube into a metal holder with threads formed in openings therein; and tiny metal discs must then be used to provide contact between the silvered surface and the condenser connection on the said holding block, which, in turn, must be insulated by means of insulation discs or washers so that the feed-through conductor is securely separated from the outer metallic coating.

It is an object of the present invention to provide inexpensive, easily made and easily assembled feedthrough capacitors, and more particularly a multiple feed-through capacitor, which can be preassembled,

or shield wall.

SUBJECT MATTER OF THE PRESENT INVENTION Briefly, a ceramic plate is formed with sleeve-like protuberances, integral therewith, and at least the surface of the plate which has the sleeve-like protuberances is covered with metalized coating. The sleevelike protuberances are formed with axial apertures, extending transverse to the major plane of the plate, through which the feed-through conductors extend. The metalized coating is so applied that it does not extend to the zone immediately surrounding the exit openings of the apertures, in order to provide ceramic material, for insulation of the feed-through conductors, from the outer metalized coating. In one aspect of the invention, the plate is entirely metalized, then the metal coating is reinforced, for example by dip soldering or the like, and the metal coating is removed by grinding from the region immediately surrounding the exit openings of the apertures through the sleeves.

The feed-through conductors may have any form, and they may broadly be termed wire means" although they may be shaped to be solder terminals, connecting pins or terminal connectors, or merely wires passing therethrough. Preferably, during the metalizing step the apertures are also metalized at their inside, and the feed-throughconductors are then soldered to the interiorly extending metal coating. The outer electrode, surrounding the sleeve, is common to all the feed-through capacitors, the inner electrode being formed by the wires passing through the apertures.

The capacitors can readily be assembled by merely passing the feed-through wires through the apertures, and, if necessary, dip soldering. Mass production is thus possible, as well as pre-assembly. A wide range of capacity can be provided.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a longitudinally sectional view through a feed-through capacitor, illustrating conductors (not sectionalized) in various position, to a greatly enlarged scale;

FIG. 2 is a topview of the FIG. 1;

FIG. 3 is a schematic illustration of a multiple feedthrough capacitor with different values of capacitance with various feed-through leads;

FIGS. 4 and 5 are a bottom view and vertical section of a ceramic body for two capacitors, and illustrating a first step in the method of production;

FIGS. 6 and 7 are a bottom view and a section of the body of FIGS. 4 and 5, metalized, and illustrating a further step in the method of production;

FIGS. 8 and 9 are a bottom view and a section of the body of FIGS. 4 and 5 illustrating another step in the method of production, in which the metal coating is refeed-through capacitor of moved, by grinding, from the face surface of the protu-.

berance, as well as from the flat surface of the plate;

FIG. 10 is the finished capacitor, with feedthrough conductors, soldered to the inner metalized coating, in section; and

FIGS. 11 and 13 are bottom views and 12 and 14 sectional views of FIGS. 11 and 13, respectively, illustrating geometrical arrangements of various types of multiple feed-through capacitors.

The feed-through capacitor of FIGS. 1 and 2 is made for six leads. A shield wall or housing 1 is formed with a suitable opening, or a plurality of suitable openings through which the feed-through capacitor is inserted. The feed-through capacitor itself, essentially, has a plate-like ceramic socket or body 2, which has integral protuberances 3 extending therefrom, in the form of sleeves. Feed-through conductors 4 are inserted through apertures formed in the protuberances 3. The protuberances 3 have an inner electrode 5 to which the feed-through conductors 4 are soldered. A common outer electrode 6 covers thelower surface of the platelike body, as well as the sleeve-like protuberances, except for the end face 7 of the protuberances, and for the upper surface 8 of the plate-like body.

In accordance with a feature of the invention, the entire surface of a fired ceramic body of the shape shown in FIG. 1 is chemically copper coated, or nickel coated by a reduction process. If necessary, the base metal layer can then be reinforced galvanically, or by dip soldering. At this stage of manufacture, the capacitor electrodes are short circuited. They are separated by grinding the metal coated ceramic body at the surface 8, and at the end surfaces 7 of the protuberances. The remainder will be an unmetalized ceramic surface, which forms the insulation part between the feedthrough conductors 4 and the remaining outer metalized coating.

The feed-through conductors 4 may be pushed through the opening, or, preferably, soldered. They may be smooth connecting wires, single or double ended terminal pins, solder connectors, solder eyes, or the like or may have any other desired suitable shape, for example be formed with a small upset as seen in FIG. 1 to limit the depths of insertion.

Some electronic designs require different values of capacity of the feed-through capacitors. To obtain such different values, the wall thicknesses of the sleeve-like protuberances can be made of different size, or the openings can be made of different size, so that when the wall thickness is small, a higher capacity will be available, than with a thicker wall of dielectric material between inner metalized coating 5, or conductor 4, and the outer coating 6.

The capacitor block may also be made of ceramic material having different dielectric constants; FIG. 3 illustrates a ceramic feed-through capacitor having dielectric materials 9, and 10, of dielectric constants of different values. The masses of ceramic material are placed in a compression matrix, for example filled at the left side with a material having a dielectric constant of 2,000, and at the right side filled with a material having a dielectric constant of 9,000. Such materials are known, which have different dielectric constants, but essentially similar firing characteristics. Thus, contraction upon cooling, sinter temperatures, vthermo expansion characteristics and the like of such materials may be similar, although of different dielectric constants, and when fired, a unitary block is produced, the individual capacitor sections of which, however, having different capacity.

FIGS. 4-10 illustrate steps in the manufacture. First,

a ceramic body 11 (which may have more than one ceramic material of different dielectric constant, see FIG. 3) is made and fired. It is then completely covered with a metal layer 12 (FIGS. 6, 7) and thereafter the top flat surface 13, and the end face surface 14 is ground, so

that metal coatings will remain only at the side surfaces 15, as well as at the inner surface 16 of the bores or apertures (FIGS. 8, 9) thereafter, the feed-through conductors 17 are inserted in the openings and soldered, for example by dip soldering, to the interior electrode, that is, metal coating 16 within the apertures of the metal body.

FIGS. 11 and 12 show a fixed-element feed-through capacitor in a particularly compact arrangement, in which a ceramic plate 18 has aperturedprotuberances 20, offset with respect to each other, .for the separate feed-through capacitors. FIGS. 13 and 14 illustrate a strip-form capacitor with a plate unit 19, from which sleeve-like, or tube-like protuberances 2l extend, to receive the feed-through conductors.

The shape of the sleeve-like protuberances can be selected as desired, for example circular (FIG. 11) or polygonal, for example square (FIG. 13).

Various changes and modifications may be made within the scope of the inventive concept.

I claim; c 1. Multiple feed-through capacitor comprising a fired ceramic plate formed with sleeve-like protuberances and apertures through said protuberances extending generally transversely to the major plate suface;

conductor means extending through the apertures of the sleeve-like protuberances;

and a metal coating covering the outer surface of the sleeve-like protuberances except for a zone surrounding the. junction of the apertures and the plate, and the protuberances,respectively, the conductor means forming one electrode of the capacitor and said metal coating the other electrode thereof.

2. Capacitor according toclaim 1, wherein the conductor means comprises an inner sleeve forming a metal coating at the side wall of the aperture; an electrical wire means passing through said inner sleeves.

3. Capacitor according to claim 2, wherein the inner sleeve and the wire means are soldered together.

4. Capacitor according to claim 1, wherein the metal coating covers the outer surface of the plate from which said protuberances project.

5. Capacitor according to claim 1, wherein the plate has one flat surface;

and the opposite surface thereof is formed with said protuberances, said flat surface being free from metal coating.

6. Capacitor according to claim 1, wherein the protuberances are of different wall thickness to provide for different feed-through capacitances.

7. Capacitor according to claim 1, wherein said ceramic plate is made of materials of different dielectrical constants, but of similar firing characteristics, and the different protuberances are located at zones of said different materials.

8. Method of making a feed-through capacitor of the type claimed in claim 1 comprising preparing a ceramic plate having protuberances projecting from the major plane of the plate, and apertures leading through said protuberances, the terminal ends of the apertures at the side of the protusaid apertures. 10. Method according to claim 8, further comprising the step of inserting electrical wire means into the apertures after said removal step. 1 11. Method according to claim 8, wherein said removal step comprises grinding off said conductive coating at least in the region of the end faces of said protuberances. 

1. Multiple feed-through capacitor comprising a fired ceramic plate formed with sleeve-like protuberances and apertures through said prOtuberances extending generally transversely to the major plate suface; conductor means extending through the apertures of the sleevelike protuberances; and a metal coating covering the outer surface of the sleevelike protuberances except for a zone surrounding the junction of the apertures and the plate, and the protuberances, respectively, the conductor means forming one electrode of the capacitor and said metal coating the other electrode thereof.
 2. Capacitor according to claim 1, wherein the conductor means comprises an inner sleeve forming a metal coating at the side wall of the aperture; an electrical wire means passing through said inner sleeves.
 3. Capacitor according to claim 2, wherein the inner sleeve and the wire means are soldered together.
 4. Capacitor according to claim 1, wherein the metal coating covers the outer surface of the plate from which said protuberances project.
 5. Capacitor according to claim 1, wherein the plate has one flat surface; and the opposite surface thereof is formed with said protuberances, said flat surface being free from metal coating.
 6. Capacitor according to claim 1, wherein the protuberances are of different wall thickness to provide for different feed-through capacitances.
 7. Capacitor according to claim 1, wherein said ceramic plate is made of materials of different dielectrical constants, but of similar firing characteristics, and the different protuberances are located at zones of said different materials.
 8. Method of making a feed-through capacitor of the type claimed in claim 1 comprising preparing a ceramic plate having protuberances projecting from the major plane of the plate, and apertures leading through said protuberances, the terminal ends of the apertures at the side of the protuberances being surrounded by end faces on the protuberances; firing said plate; metalizing surfaces of said plate to form a conductive coating thereon; and removing said conductive coating in zones surrounding said apertures.
 9. Method according to claim 8, further comprising reinforcing said layer of conductive coatings; and wherein the removing step comprises removing said reinforced coating in said zone surrounding said apertures.
 10. Method according to claim 8, further comprising the step of inserting electrical wire means into the apertures after said removal step.
 11. Method according to claim 8, wherein said removal step comprises grinding off said conductive coating at least in the region of the end faces of said protuberances. 